The present invention relates generally to external bolsters of the type used to retain an implanted medical catheter in the body of a patient and relates more particularly to external bolsters of the aforementioned type that include means for relieving strain applied to the medical catheter.
Certain patients are unable to take food and/or medications transorally due to an inability to swallow. Such an inability to swallow may be due to a variety of reasons, such as esophageal cancer, neurological impairment and the like. Although the intravenous administration of food and/or medications to such patients may be a viable short-term approach, it is not well-suited for the long-term. Accordingly, the most common approach to the long-term feeding of such patients involves gastrostomy, i.e., the creation of a feeding tract or stoma between the stomach and the upper abdominal wall. (A less common approach involves jejunostomy, i.e., the creating of a feeding tract or stoma leading into the patient's jejunum.) Feeding is then typically performed by administering food through a catheter or feeding tube that has been inserted into the feeding tract, with one end of the feeding tube extending into the stomach and being retained therein by an internal anchor or bolster and the other end of the feeding tube extending through the abdominal wall and terminating outside of the patient.
Although gastrostomies were first performed surgically, most gastrostomies are now performed using percutaneous endoscopy and result in the implantation of a feeding tube/internal bolster assembly (also commonly referred to as a percutaneous endoscopic gastrostomy (PEG) device) in the patient. Two of the more common techniques for implanting a PEG device in a patient are “the push method” (also known as “the Sacks-Vine method”) and “the pull method” (also known as “the Gauderer-Ponsky method”). Information regarding the foregoing two methods may be found in the following patents, all of which are incorporated herein by reference: U.S. Pat. No. 5,391,159, inventors Hirsch et al., which issued Feb. 21, 1995; U.S. Pat. No. 5,167,627, inventors Clegg et al., which issued Dec. 1, 1992; U.S. Pat. No. 5,112,310, inventor Grobe, which issued May 12, 1992; U.S. Pat. No. 4,900,306, inventors Quinn et al., which issued Feb. 13, 1990; and U.S. Pat. No. 4,861,334, inventor Nawaz, which issued Aug. 29, 1989.
According to the push method, one end of an endoscope is intubated (i.e., inserted) into a patient's mouth and is passed through the esophagus into the stomach. After distension of the stomach by inflation, an entry site on the abdomen is identified using the endoscope for transillumination, and an incision is made by passing the tip of a needle coupled to an outer cannula through the abdominal and stomach walls and into the stomach. One end of the outer cannula remains outside of the body and acts as a stop to prevent the external end of the needle from falling into the stomach. A snare is inserted into the stomach via the endoscope and is looped over the inserted end of the needle. The snare is then “walked” up the needle until the outer cannula is snared. The snared cannula is then pulled externally to tack the cannula to the stomach and, in turn, to secure the stomach wall to the abdominal wall. The needle is then removed while keeping the cannula in place. A first end of a flexible guidewire is then passed through the cannula and into the stomach where it is grasped by the snare, the second end of the guidewire remaining external to the patient. The endoscope and the snare are then withdrawn from the mouth of the patient to deliver the first end of the guidewire.
A push-type catheter implanting assembly is then inserted over the first end of the guidewire and is pushed over the guidewire towards its second end. The push-type catheter implanting assembly typically comprises a gastrostomy feeding tube, the gastrostomy feeding tube having a dome-shaped internal bolster disposed at its trailing end and having a tubular dilator serially connected to its leading end. The gastrostomy feeding tube and the internal bolster are typically made of a soft, biocompatible material, like silicone rubber, and may form a unitary structure. The dilator, which tapers in outer diameter from its trailing end to its leading end, is typically made of polyethylene or a like material which is stiffer than silicone but which still possesses some flexibility. Advancement of the push-type catheter implanting assembly over the guidewire continues until the front end of the dilator reaches the cannula and pushes the cannula out through the abdominal wall of the patient. The front end of the dilator is then pulled through the abdominal wall until the front end of the gastrostomy feeding tube emerges from the abdomen and, thereafter, the internal bolster at the rear end of the gastrostomy feeding tube engages the stomach wall. The guidewire is then removed from the patient. The clinician then re-intubates the patient with the endoscope and uses an optical channel in the endoscope to inspect whether the internal bolster is properly seated in the stomach.
If the internal bolster is properly placed against the stomach wall, a length of the externally-extending portion of the implanted gastrostomy feeding tube is then typically cut and removed from the implanted tube to reduce the externally-extending portion of the tube to a desired length (typically about 4-6 inches). (The removal of the leading end of the gastrostomy feeding tube also results in the removal of the dilator, which is connected thereto.)
The pull method is similar in some respects to the above-described push method, the pull method differing from the push method in that, after the cannula is snared and the needle is removed therefrom, a first end of a suture is inserted through the cannula and into the stomach where it is grasped by the snare, the second end of the suture remaining external to the patient. The endoscope and the snare are then withdrawn from the mouth of the patient to deliver the first end of the suture. The first end of the suture is then coupled to the leading end of a pull-type catheter implanting assembly, the pull-type catheter implanting assembly typically comprising a gastrostomy feeding tube having an internal bolster at its trailing end and a plastic fitting at its leading end. The plastic fitting typically has a barbed rear portion mounted within the leading end of the feeding tube and a conical front portion that serves as a dilator, said conical front portion tapering in diameter from the leading end of the feeding tube to a front tip. A wire loop is fixed to the front tip of the plastic fitting, the first end of the suture being tied to the wire loop. Using the second end of the suture, the pull-type catheter implanting assembly is then pulled retrograde through the patient until the gastrostomy feeding tube emerges from the abdomen of the patient and the internal bolster engages the stomach wall of the patient. Next, as is the case in the push method, the clinician then re-intubates the patient with the endoscope in order to visually inspect the placement of the internal bolster within the stomach. If the bolster is properly seated in the stomach, the externally-extending portion of the implanted gastrostomy feeding tube is then typically cut to a desired length.
Regardless of whether a PEG device is implanted by the above-described push method, by the above-described pull method or by another method, complications may arise if the PEG device is positioned too far internally within the patient. More specifically, if the trailing (i.e., internal) end of the PEG device, especially the internal bolster, is positioned too far internally within the patient, the PEG device can cause blockages in the patient's stomach or otherwise interfere with stomach function. Furthermore, if the trailing end of the PEG device is positioned too far internally within the patient, the leading (i.e,. external) end of the PEG may be drawn entirely into the patient's stomach, possibly causing great harm to the patient.
For the above reasons, it is customary to use an externally located device, typically referred to in the art as an external bolster, to retain the external portion of the PEG device outside of the patient. An external bolster typically comprises an enlarged annular member that is shaped to include a central bore through which the external portion of the PEG device may be inserted. Preferably, the central bore is appropriately dimensioned to provide an interference (i.e., frictional) fit between the external bolster and the feeding tube fed therethrough. In use, the leading (i.e., external) end of the implanted PEG device is inserted through the central bore in the external bolster as far as possible. Due to the significant interference fit between the outer diameter of the feeding tube and the inner diameter of the external bolster, forceps or the like may be used to facilitate the insertion of the leading end of the feeding tube through the central bore of the external bolster. The feeding tube is preferably advanced through the central bore until the bottom surface of the external bolster is drawn into direct contact with the patient's skin in the area surrounding the wound site. Positioned in this manner, the external bolster effectively anchors the implanted PEG device in its proper position and prevents any migration of the device into the patient's stomach. Although not needed in all cases, it may be desirable in certain instances for the external bolster to be sutured to the patient's skin.
Although external bolsters of the type described above function satisfactorily to prevent the external end of an implanted PEG device from being withdrawn into a patient's stomach, most such external bolsters do not additionally provide strain relief to dissipate the effect of an externally-directed pulling force applied to the PEG device. Such strain relief is highly desirable as it has been found that certain patients (e.g., patients suffering from dementia or Alzheimer's disease) often knowingly or unknowingly attempt to remove implanted PEG devices from their bodies by pulling on the external end of the PEG device. As can be readily be appreciated, the application of a sufficiently great pulling force on the external end of an implanted PEG device can ultimately result in, among other things, the ill-advised removal of the PEG device from the patient and/or significant injury to the patient at the site of implantation (e.g., tearing of sutures, damage to the stoma, etc.).
In response to the above problem, certain external bolsters have been devised that provide strain relief to an implanted feeding tube. For example, in U.S. Pat. No. 6,471,676, inventor DeLegge, which issued Oct. 29, 2002, and which is incorporated herein by reference, a catheter retention device is disclosed that is designed to relieve strain caused by physical force exerted against the catheter. The retention device, which is unitary in design and constructed out of a flexible material, such as silicone or thermoplastic rubber, includes a base component which supports first and second substantially cylindrical retention ring housing components, the second retention ring housing component being positioned on the base such that the axis of its centrally disposed bore is out of axial alignment with the centrally disposed bore for the first retention ring housing component. In use, the portion of an implanted feeding tube which exits the patient's body is first passed through a bore formed in the base component. The feeding tube is then curved at approximately a ninety degree (90°) angle and is threaded through the central bore of the first retention ring housing component. The feeding tube is then looped around at an angle of approximately two hundred-seventy degrees (270°), preferably on a plane parallel to the base component so as to be threadably insertable through the central bore of the second retention ring housing component whose axis is perpendicular to that of the bore of the first retention ring housing component. Once the feeding tube is fed through the base component and both retention ring housing components as described above, the base is attached to the skin of the patient using any one of a number of attachment means or methods known in the art such as sutures, staples, adhesive tapes or liquid adhesives.